Hammy already starts working upon activation, so any configuration is optional:

Upload the folder hammy to the /wp-content/plugins/ directory

Activate the plugin through the 'Plugins' menu in WordPress

(Optional) Go to Settings -> Hammy and review the options. Add the id/class of the container that holds your posts (i.e. #content). Then add breakpoints that are relevant to that container ( see the FAQ for an example ).

(Optional) Edit your theme's CSS to add figure.hammy-responsive, in a way that it is identical to any img styling used for your content area.